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Power wiring diagram for boscam 5.8ghz tx, 808 #16v2 with quad's power system

#1
Hi all,
I just ordered my boscam 5.8ghz tx and rx set with the 808#16v2 camera. I read somewhere that you can power the fpv system through the balance plug from the quad's main power system. I have a homemade 450mm quad that runs 1500kv BW swinging 8x4 props. It can run on both 3s and 2s. I was wondering if the pros out there could show me how they power up their fpv systems without adding another battery.

Thanks
 
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Johan

Senior Member
#2
Hi Nguyen,

I'm not a pro, but I have the same setup.

I use the internal power of the 808 #16 for the camera itself, this gives you about 40 mins of recording/video out.
Mind you: it can cut out when the internal battery is not charged fully!!

On my Batbone tri I regretted getting the 1 to 3 splitter power cord, it gives less clutter, but did not give me an extra power connection.
So I added a splitter (for people that start out I'd recommend getting the 1 to 4 splitter cord, this leaves you with an extra power cord for extensions like an FPV).
I run the Boscam transmitter on that extension (my Boscam Tx can handle 3S, but you have to check to make sure, I've read that on the receiver end there are 5V and 12V versions....).

I did not connect the power lead from the Boscam to the 808, to make sure not to overpower the cam, but others may have succeeded.
 
#3
If the 5.8Ghz transmitter is rated for 5V, just pull the 5 volts from motor port 8 on the KK2 (port 2 through 8 are on the same rail and will get power from any of the ESCs connected in the string).
 
#4
Hi Johan,
Thanks for the reply. Just to clarify something, the splitter you mentioned means the power harness that you use for the esc/motor? You're adding another branch to power the TX? Do you see any changes in the performance/flight time?


Hi Nguyen,

I'm not a pro, but I have the same setup.

I use the internal power of the 808 #16 for the camera itself, this gives you about 40 mins of recording/video out.
Mind you: it can cut out when the internal battery is not charged fully!!

On my Batbone tri I regretted getting the 1 to 3 splitter power cord, it gives less clutter, but did not give me an extra power connection.
So I added a splitter (for people that start out I'd recommend getting the 1 to 4 splitter cord, this leaves you with an extra power cord for extensions like an FPV).
I run the Boscam transmitter on that extension (my Boscam Tx can handle 3S, but you have to check to make sure, I've read that on the receiver end there are 5V and 12V versions....).

I did not connect the power lead from the Boscam to the 808, to make sure not to overpower the cam, but others may have succeeded.
 
#5
If the 5.8Ghz transmitter is rated for 5V, just pull the 5 volts from motor port 8 on the KK2 (port 2 through 8 are on the same rail and will get power from any of the ESCs connected in the string).
THanks Mustang.
Does that mean you have to make a custom wire for it? I'm not able to imagine the setup yet. Sorry for my noob-ness, I'm still new to this.
 

Johan

Senior Member
#6
With a quad and KK2 you'll normally use ports 1..4 for ESC's, so ports 5..8 are 'spare'

When it comes to power: port 1 has its own separate +5V, separated from ports 2..8.
Port 1 receives power from the left front motors ESC.

For port 2..8 the +5 is common to all ports.
If you want to draw power from one of the 'spare' ports, connect black/brown to GND and the red cable to +5V.

As said, the No 2 .. No 8 ports on the KK2 share a common +5 and GND.
So the power/GND on these are connected (soldered) through, so only one one NEEDS to receive power.

The power comes from any ESC connected to one of these ports (say the ESC of motor 2, unless it is an OPTO (no BESC, meaning no +5V power regulator)).

In some cases you can can connect all 3 remaining ESC's unmodified to ports 2..4, BUT: not all ESC's allow you to connect in parallel, since the 5V they put out is interconnected by the KK2.

Then the option is to remove (I did not cut, but gently removed and folded back) the red (+5V) cables from the other ESC's so that only one is connected to ports 2..8

(Man this is hard to describe, can you still follow?)

Anyway, that is why OPTO ESC's exist: this allows you (for a quad) to buy two regular ESC's (port 1, port2) to power the separate circuits (1 and 2..8) and connect the two OPTO ESC's to port 3 and 4 (not delivering power).
Port 1 actually powers your transmitter ...

xuzme720, as a native speaker, please help if something is not clear :)
 

xuzme720

Dedicated foam bender
Mentor
#7
With a quad and KK2 you'll normally use ports 1..4 for ESC's, so ports 5..8 are 'spare'

When it comes to power: port 1 has its own separate +5V, separated from ports 2..8.
Port 1 receives power from the left front motors ESC.

For port 2..8 the +5 is common to all ports.
If you want to draw power from one of the 'spare' ports, connect black/brown to GND and the red cable to +5V.

As said, the No 2 .. No 8 ports on the KK2 share a common +5 and GND.
So the power/GND on these are connected (soldered) through, so only one one NEEDS to receive power.

The power comes from any ESC connected to one of these ports (say the ESC of motor 2, unless it is an OPTO (no BESC, meaning no +5V power regulator)).

In some cases you can can connect all 3 remaining ESC's unmodified to ports 2..4, BUT: not all ESC's allow you to connect in parallel, since the 5V they put out is interconnected by the KK2.

Then the option is to remove (I did not cut, but gently removed and folded back) the red (+5V) cables from the other ESC's so that only one is connected to ports 2..8

(Man this is hard to describe, can you still follow?)

Anyway, that is why OPTO ESC's exist: this allows you (for a quad) to buy two regular ESC's (port 1, port2) to power the separate circuits (1 and 2..8) and connect the two OPTO ESC's to port 3 and 4 (not delivering power).
Port 1 actually powers your transmitter ...

xuzme720, as a native speaker, please help if something is not clear :)
Looks like you got it all right, Johan, except for the very last bit. Port 1 powers both the KK2 and sends power to the radio's receiver, not the transmitter.

The only other thing I would add is this: On a quad, you have no servos to power, so the 2-8 ports actually don't need to be powered by any of your ESC's unless you need a 5VDC supply for something else. Keep in mind that you can also pull 5V power is from a spare channel on the Rx.

Where ever you get your power from, make sure you do not reverse the polarity! Ground is the pins to the outside of the board, and you will need to check the receiver to see which pins are ground on there. Positive voltage will be delivered on the middle pin.
 

xuzme720

Dedicated foam bender
Mentor
#8
I just went and looked and it shows you're going to need 12v to power the video Tx. That will have to come from a 3S battery. If you are running the 2S, there really isn't anyway around a second battery except for a step up dc converter, but I'm afraid that will introduce noise into your video.

Best thing to do is get a balance plug that your battery's balance plug will plug into, and use the outside wires to connect power to your video transmitter. Once again, make sure the polarity is correct or you will have to buy another video transmitter!
HP-EOSLBA-MC-A5.jpg
On this one in the picture, the red wire would go to your red wire on the transmitter and the last black would go to black on the transmitter.

(The plug shown there is also for a 5S battery, a 3S will only have 4 wires.)
 
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Johan

Senior Member
#9
Looks like you got it all right, Johan, except for the very last bit. Port 1 powers both the KK2 and sends power to the radio's receiver, not the transmitter.

The only other thing I would add is this: On a quad, you have no servos to power, so the 2-8 ports actually don't need to be powered by any of your ESC's unless you need a 5VDC supply for something else. Keep in mind that you can also pull 5V power is from a spare channel on the Rx.
LOL, yes, powering the transmitter from your quad would be, well to quote David "that would be awkward".
So, consider that a typo (I meant receiver).

Having a tri (no quad) myself, I din't realise that for a quad there is nothing on the other ports that requires power..
Also using a spare channel from the transmitter, that is a neat trick!

Be sure to not overrate the power rating (current rating) of the ESC with the components that are powered by it .

But with ESC's rated at 2A (on the +5v output) there is room to spare ...

[EDIT: I mentioned the Boscam consuming ~200mA, but of course it is not powered from the 5V ESC, it is powered directly from the 3S]
 
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xuzme720

Dedicated foam bender
Mentor
#10
But will the boscam run on 5V? the site says it needs to be 12V...

As far as powering the transmitter from the quad, well, lets just say there would be little risk of losing the quad since you would have to fly VERY close in!
 
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Johan

Senior Member
#11
But will the boscam run on 5V? the site says it needs to be 12V...

As far as powering the transmitter from the quad, well, lets just say there would be little risk of losing the quad since you would have to fly VERY close in!
Sorry, now I was giving confusing information:
Indeed I power the Boscam from the 12 V splitter, not the spare 5V outputs, sorry for that confusion. Ill correct that...

Powering the Transmitter from the quad
Yeah, just like the guys with the quad on the wired power line article !!
 
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xuzme720

Dedicated foam bender
Mentor
#12
Low voltage usually doesn't hurt anything, so no harm done. going the other way is very bad however and a good way to let out the magic smoke...
 
#14
hi guys, thanks for your clarification. So basically i can either get the power directly from the balance plug or get it through the kk2 board spare ports. Both require some modification to the power wire. And I have to make sure the voltage is matching too. Am i missing anything else?

p/s if the tx calls for 12V but I'm running on 2s would it work? would it damage the tx?
 

xuzme720

Dedicated foam bender
Mentor
#15
12V can only be pulled from a 3S battery. 5V can be pulled off the boards spare ports. We were confused over what voltage we were talking about. You will need to get 12v power from the 3S battery only.
A 2S pack only provides 8.4v total at full charge so probably will not power the Tx. You can give it a try, as some Tx's will work on a lower voltage, but the Tx power will have to come from the battery and not the board.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#17
*if* the transmitter can run on 5v, and *if* the transmitter won't pull so much current it won't brown out the controller and receiver, then maybe, but not of one of the KK2 ESC ports.

two things:

From the listings on HK's site, the boscam TXs drop off at 7v. It may still work but it might depend on manufacturer's tollerances since it's outside the designed specs. Even if it does work, there's a fair chance of poor performance (lower output or poorly tuned signals).

KK2 ESC grounds are tied togther, but the power pins are isolated -- if they weren't the UBECs in the ESCs would fight and likely two or more would burn out. Only port 1 needs to be connected to a UBEC, but the remaing 7 are routed nowhere. if you try to draw off, say port 8, you will be grounded but you will get no power from the other 3 ESCs. you *could* pull out one of the ESC's power lines (from ports 2-3, NOT port 1), and connect it to the boscam power line, but that's a messy connection.


Really, consider using the balance port. It is the cleanest solution, and you'll have less chance of browning-out your control board and/or receiver from low voltage, and your TX will get the voltage it needs..
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#19
Yes, that will work, but with the JST style balance plugs (comes on the turngey batteries, and possibly more), the pin size and spacing will work with any single row PCB header like:

http://www.amazon.com/2-45mm-Pitch-Position-Single-Header/dp/B005HN237S/ref=sr_1_3?ie=UTF8&qid=1382629411&sr=8-3&keywords=pcb+header

This can be ordered, or purchased locally at any good electronics parts store.

To use, cut to length (3 pins for 2S, 4 pins for 3S), solder the power leads to the two end pins, and cover the non-pin end in shrink tubing or hot glue (lay soldered connection on a metal surface/ruler, quickly apply hot glue to one side, flip, apply to the other, then press with another ruller or flat metal plate until cool -- cut away excess).

If you choose to make your own, take care to match polarity (black-to-black) when plugging in -- the plug you linked will ensure polarity is correct.
 
#20
Craftydan, thank you very much for the instructions. I actually just ordered some jst-xh plug from china. Will make sure polarity matches.

Thanks again everyone